A sliding bearing formed cylindrically by abutting a pair of half bearings to each other and provided with a chamfered part and a crush relief on an inner peripheral portion of a joining surface of each of the half bearings is known (See FIG. 6). In a sliding bearing provided with a crush relief such as a notch part, as illustrated in FIG. 6, when lubricant oil is supplied from an oil hole in a crank shaft, foreign substances mixed in the lubricant oil are caught by the crush relief and then discharged to the outside through the crush relief or openings on side parts on the chamfered part.
Sliding bearings in which foreign-substance discharge grooves are formed at required spots on a sliding surface in order to catch and discharge the foreign substances mixed in the lubricant oil to the outside have been proposed (See Patent Literatures 1 to 3, for example).
In the sliding bearing in Patent Literature 1, an oil groove is provided over the whole region in the circumferential direction on the sliding surface of the lower half bearing, and a pair of foreign-substance discharge grooves opened in the end faces in the axial direction of the half bearing is formed by branching the oil groove.
Also, the sliding bearing in Patent Literature 2 is formed by pivotally supporting a rotary shaft by a plurality of arc-shaped pads, a T-shaped groove for catching the foreign substances is formed on the sliding surface of each of the arc-shaped pads, and a magnet is installed on the bottom part of the axial grooves in a T-shaped groove. The magnet adsorbs and catches the foreign substances in the axial groove.
Moreover, in the sliding bearing in Patent Literature 3, a plurality of linear foreign-substance discharge grooves are formed in the axial direction in the vicinity of an joining surface in the lower half bearing.